Locusts Agriculture and Weather

Types of Locusts Australian Plague Locust Spur Throated Locust Migratory Locust

Male or Female Male - tip of abdomen smooth and rounded Female - tip of abdomen jagged

Conditions for locusts Egg development is strongly influenced by temperature and moisture conditions Outbreaks of the locust can occur if good rain falls over two consecutive years, allowing 3-5 generations to develop in each year. Winter rain is of importance to locusts, as the eggs do not cannot survive prolonged dry periods. The Australian plague locust and spur-throated locust normally mature eggs only after rain has produced green vegetation. The migratory locusts mature their eggs even on drying vegetation. If the eggs are laid in dry soil and no follow-up rain occurs high mortality occurs.

continue The Australian plague locust can reach plague proportions within a year if a sequence of widespread heavy rains occur in inland areas, particularly during summer, allowing them to complete several generations of increase. Less regular rains, falling in both the interior and in the agricultural zone of eastern Australia, can maintain high density gregarious populations for several years, and continue a plague cycle. Prolonged dry periods usually result in a population decline to background levels. An outbreak cycle may involve exchange migrations between regions of summer and winter rainfall, and the persistence of high density populations of agricultural regions of inland southeastern Australia. Heavy summer rainfalls in western Queensland often lead to large population increases and subsequent southward migrations in late summer and autumn. This pattern has characterised several of the recorded major pest outbreaks, or plagues.

Current forecast for spring health/locusts/current

Damage

Reproduction

Control The most effective way for landholders to control locusts is by ground spraying the hoppers when they have formed into dense aggregations called bands. The time available for controlling an outbreak of locusts is short. Hoppers take about 5 weeks to develop into swarming adults. Hoppers are much easier to control than swarming adults. The hoppers usually take 1-2 weeks after hatching to form into dense bands suitable for spraying. Ploughing fields where locusts have laid eggs may have some impact on individual egg beds, but egg laying often occurs in areas where ploughing is not possible (for example, in hard soil along roads or tracks). Although there are a number of natural enemies of locusts such as birds, spiders and insects, none are able to effectively regulate locust numbers during an outbreak.natural enemies